PROJECT SUMMARY We propose a multi-tiered Maximizing Access to Research Careers at the University of California Santa Barbara (MARC- UCSB) program that continues the successes of our current MARC program and increases retention and matriculation into PhD and MD/PhD programs of all undergraduates (but especially underrepresented [UR] and disadvantaged students) interested in pursuing careers in biomedical research. Nationwide, and at UC Santa Barbara, the greatest loss of UR students from STEM fields occurs during the first two years. Consequently, the first phase of the MARC-UCSB program will begin with a series of engagement points for MARC?eligible students that stimulate new points of entry into research and scientific community, and integrate into existing infrastructure at UCSB. These engagement points will include: gateway classroom outreach and early research experience; a mentoring network of peers, graduate students/postdoctoral scholars, and faculty; and an introduction to research course called the ?Practice of Science.? As they build community and increase awareness of various research and career opportunities, students will be prepared to further develop as researchers through the next phase of MARC-UCSB: the two-year MARC Scholars program, and accompanying MARC Affiliate initiatives. Ten motivated students will be selected as MARC Scholars each year. In addition to acquiring extensive research experience, they will grow their leadership skills through various professional opportunities such as presenting at conferences, serving as mentors for lower division students, and developing a team-based community service project in the service-learning course ?Science for the Common Good?. Although 50 students will receive MARC scholarships, an additional ~100 MARC-Affiliates will be impacted by our activities and will be well-prepared to apply for other synergistic research internship programs and eventually to advanced degrees and careers in biomedical research. Underpinning this Scholar retention and success will be a suite of faculty and graduate student/postdoc mentor training initiatives integrated into developing infrastructure to impact the training landscape for sustained impact. Through the MARC-UCSB program our long-term goals are to: a) enhance an institutional culture where students are immersed into a cohesive social, academic, and research community that nurtures their success from an early stage; b) cultivate students? confidence and skills to enable them to matriculate into and succeed in top advanced degree programs; and c) grow and maintain an institutional culture of mentoring excellence to create a more inclusive environment for our entire STEM campus community. We propose a three-pronged approach to achieve this that will: 1) apply ?proposed innovations? to meet our objectives and address challenges in our current program, 2) expand ?best practice elements? that have been core features of our current successes, and 3) leverage ?synergistic infrastructure? from institutional elements that will contribute to achieving MARC-UCSB objectives. As the first of only three in the Association of American Universities (AAU) to reach Hispanic Serving Institution (HSI) status, UCSB is on a short list of prominent research-intensive institutions serving a large number of Hispanic undergraduates. As such, we will have many eligible applicants to PhD and MD/PhD programs and success of this program will serve as a model for other similar R-1 institutions.